The maximum level you can enhance your weapon to in AQWorlds is currently 35 I think. (You have to unlock the higher enhancings by leveling up.)

yes IT can enhance the IQ level of children because IT provides lots of information for a school going child

All armours are already enhanced when you get them. So you can't enhance armour. But you have to be a member to enhance a cape, sword, etc if you want to enhance it above level 8.

To enhance the pH level of the water

To raise or lift up; to exalt., To advance; to augment; to increase; to heighten; to make more costly or attractive; as, to enhance the price of commodities; to enhance beauty or kindness; hence, also, to render more heinous; to aggravate; as, to enhance crime., To be raised up; to grow larger; as, a debt enhances rapidly by compound interest.